Socket errors in test suite: `socket.error: [Errno 56] Socket is already connected`

[larsbutler]

More detailed output is here: http://pastebin.com/UnYMaLKe

This is happening when I run the test suite on OSX. This does not occur on Linux (Ubuntu 12.04). I've narrowed down the issue to the use of socket.connect followed by a socket.sendto: according to the docs, you shouldn't do this.

I made a small script to reproduce the problem, and have confirmed the differing behaviors on OSX and Linux.

import socket

receiver = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sender = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

addr = ('127.0.0.1', 27000)
receiver.bind(addr)
sender.connect(addr)

num_bytes = sender.send(b'foo')
print('Received: %s' % receiver.recv(num_bytes))

num_bytes = sender.sendto(b'bar', addr)
print('Received: %s' % receiver.recv(num_bytes))

On Linux, the output is:

Received: b'foo'
Received: b'bar'

On OSX, the output is:

Received: foo
Traceback (most recent call last):
  File "socktest.py", line 13, in 
    num_bytes = sender.sendto(b'bar', addr)
socket.error: [Errno 56] Socket is already connected

I've tested this script with multiple versions of Python, and the behavior is the same: the Linux socket implementation is more forgiving.